Update Kubernetes upgrade plan

Update Kubernetes upgrade plan

Kubermatic provides live updates of your Kubernetes cluster
without disrupting your daily business. The allowed updates are defined in the file
updates.yaml. You find it in your Kubermatic installer clone directory:

As you can see it is a list containing the keys from, to, and automatic. The fields
from and to contain patterns descibing the Kubernetes version numbers. These can be absolut,
contain wildcards, or be ranges. This way Kubermatic can check which updates are allowed for
the current version.

The field automatic determines if an update has to be initiated manually or if the system will
do it immediatelly in case of a matching version path. So in case of the example above a cluster
running in any Kubernetes version from 1.12.0 to 1.12.2 would automatically upgrade to 1.12.3.
This way known vulnerabilities can be handled directly.

Note: The automatic update only updates the control plane. Kubelets on the nodes still have
to be updated manually.